1. Field of the Invention
This invention relates to lubricants for synthetic fibers such as incorporated with mono- and multi-filament polyester and nylon yarn and particularly to fiber lubricants having improved resistance to oxidative degradation at elevated temperatures of at least over 200.degree. C. Such lubricants are suitable for use in producing a synthetic continuous filament, false twist, textured yarn as well as other yarns.
2. Description of the Prior Art
The production of yarns from organic linear synthetic polymers such as polyesters and polyamides requires the formation of a yarn by a suitable spinning method such as melt-spinning, wet-spinning or dry-spinning. Improved properties can be obtained when such yarns are heat set. In the production of so-called "bulky" yarns, the yarns must be heat-treated to set the shape of the yarn. The various thermo-treatments required are of necessity performed at very high speed as disclosed in U.S. Pat. No. 3,446,734 in which a process for the production of nylon tire cord is disclosed. In such processes yarn coated with about 1% of a so-called lubricating composition is subjected to temperatures of 180.degree. C to 225.degree. C during the processing.
A yarn or fiber lubricant generally must provide, in addition to lubricity, antistatic properties and emulsification or solubilization properties to enable easy removal of the lubricant from the yarn or fiber prior to the dyeing operation. In the preparation of fiber lubricant compositions, it is conventional to utilize adjuncts to the principal components of the composition such as antistatic agents, emulsifiers, oxidation stabilizers, etc.
The above lubricant properties should not be lost upon exposure of the yarn to temperatures at least above 200.degree. C by either or both the oxidative degradation of the lubricant or the volatilization of the lubricant. Conventional lubricants for synthetic thermoplastic textile fibers generally suffer from the defect that at temperatures such as at least above 180.degree. C the lubricants fume indicating volatilization and/or form a tar-like, resinous material. A heated metal plate which is in contact with the yarn during a part of the processing to impart better heat transfer is usually the site at which such resinous materials are deposited.
The need for oxidation resistance in a fiber lubricant is often indicated upon storage of lubricant treated fibers over prolonged periods of time. It is under such conditions that a yarn lubricant stabilized with an oxidation stabilizer such as certain phenols, aryl sulfonamides, phenothiazines, etc., will discolor usually with the formation of a characteristic color. The formation of insoluble resinous compounds and bacterial growth can also result from the use of certain yarn lubricants under such storage conditions.
The use of difunctional phenols and aromatic substituted glycidyl ethers, preferably phenyl glycidyl ethers, in the preparation of improved oxidation stable polyoxyalkylene compounds for use as fiber lubricants, wherein said oxidation stable fiber lubricants are resistant to yellowing upon exposure to an atmosphere in which oxides of nitrogen are present, is an unexpected advantage of the improved oxidation stable polyoxyalkylene fiber lubricants disclosed herein.
It is known to produce, as yarn lubricants, heteric polyoxyalkylene monoesters of stearic acid or lauric acid from U.S. Pat. No. 3,925,588 and British Pat. No. 1,460,960. Such lubricants have insufficient heat resistance and exhibit an undesirable high volatility at elevated temperatures at which they are used. It is known to produce heat stabilized polymers of alkylene oxides by mixture of phenothiazine therewith from U.S. Pat. No. 2,786,080 and U.S. Pat. No. 3,326,849. Antioxidants for polyoxyalkylene compounds are also disclosed in U.S. Pat. No. 3,146,272. Various monofuctional phenolic compounds such as phenothiazine, phenol and alkylated phenols which are known to be useful as additives to improve the oxidation stability in polyoxyalkylene compounds are utilized as initiators in the production of oxidation stable polyoxyalkylene compounds. Said phenolic compounds are useful in admixture with oxidation-susceptible polyoxyalkylene compounds wherein the alkylene radicals contain 2 to 4 carbon atoms.
Stabilized lubricants for nylon and polyester fibers are also disclosed in Japanese Pat. No. 76-70,397. In this reference there is disclosed a mixture of a polyethylene glycol castor oil ester and, as a stabilizing component, a bis propoxylated bisphenol A ether dilaurate. Esters of polyoxyalkylene diols initiated using an aliphatic dihydroxy alcohol are disclosed in U.S. Pat. No. 2,457,139 and U.S. Pat. No. 3,756,972.
The use of a difunctional phenol such as resorcinol as an initiator in the preparation of polyoxyalkylene surfactants is disclosed in U.S. Pat. No. 2,674,619. In U.S. Pat. No. 3,036,118 there is disclosed the production of conjugated polyoxyethylene-polyoxypropylene surfactants using initiators having at least two reactive hydrogen atoms. Fiber-treating compositions having improved heat resistance and reduced high temperature volatility and containing an ester of an ethoxylated aryl phenol are disclosed in U.S. Pat. No. 3,578,594. The use of aromatic substituted alkylene oxides in the production of polyoxyalkylene compounds is disclosed in U.S. Pat. No. 2,677,700.